Aseeand glimpse af Early Cambrian life: new calleetians from Sirius Passet, North Greenland John S. Peel, Simon Conway Monis and Jon R. Ineson Thc German mining term lagerstatren, referring to a similar age to thc Chcngjiang f<:luna of YlIllnan Prov­ rock af any composition containing constitucnts af eco­ ince, China (ehen Jun-yuan & Erdtmann, 1991; ehen nomic intcrcst, has becn widdy applied to occurrences Jun-yuan el al., 1991; Hou Xian-guang & Bcrgstrom, af abundant ar unusually well preserved fossils (cf. Sei­ 1991). lacher et al., 1985). The Middle Cambrian Burgcss The most notcworthy rnernbers ol' the Sirius Passet Shale af western Canada is perhaps the most famolls af fauna are articulated halkieriid warms (Fig. l; Comvay all fossil-Jagerst3Ue, with man)' uf the approximately Morris & Peel. 1990; Peel, 1991). but thc arthropod­ 140 known species preserving exquisite details of the dominated fauna 'lisa yiclds spanges, warms and sevcral soft anatomy af members af a community of organisms organisms of problematie affinities.. that was fossilised more than 500 million years ago (Whittington, 19R5: Conway Monis, 1979, 1986; Gould. 1989). Other well known examp1es includc the Upper Cambrian 'Orsteo' ol" southcrn Sweden, the Lowcr Devonian I-!unsriick Slate and the Jurassic Soln­ hofen Limestone uf Germany (Sti.irrner el al.. 1980; Miiller. 19R5; Barthcl el al. 1990; summary in I3riggs & Crowther, 1990, pp. 266-297). The term ean be applied aptly to the Sirius Passet fauna af central North Green­ land. where a \vcalth af exccptiunally preserved fossils (c.g. Fig. 1) from tile Lower Cambrian Buen Forn;ation has been recorded from a small tocality in western Peary Lancl. neal' the south-wesrern end af tlle hroad valley knO\vn as Sirius Passet (Fig. 2). The locality yiclding the Sirius Passet fauna \\'as dis­ covered in 1984, but substantial cullecting was first pos­ siblc in 1989 (Conway Morris rI al.. 1987; Conway Mor­ ris & Peel, 1990; Peel, 1990). At that rime, a cullectiun uf sUlne 1500 slabs of muclstone was secured, yielding a fauna ol' more tllan 30 species. Intere:-;t in the SirilIs Passet fauna reflecrs not only the anatomica] informa­ tion whieh ean be derived from spccimens prescrving details af limbs and saft parts, but alsa tlle great antiqui~ ty of the locality. The assemhlagc is significantly older Ihan the Rurgess Shale lagcrstilttcn ol' Canada, and af Fig. I. Articu!<ncd halkicriid from the Buen FOflllation at Sirius Passet. central Nonh Grccn[and. MGUf-/ [(j.72i:) from GGU col1ection 340103, X 2. Thc worm-like body is covcred by many ilundrcds af Sll1(lll sc!crites. witil prominent shclls locatcd anlcriorly (tumet! to the right il1 this spccimcn) and posteriorly. 49 ~ ~, ': :-:~-~-:: ;'''-' '. ~;=} _J'-'---' J.P." Koch p e a r y L a n d =- ~"I"'!'I! .. -; a ..;r,,'/J ',', /') /r:':' '~~-' ~-~,-:,~~--- , , Wandel Valley Formation (Ordovician) Ordoviclan U Tavsens Iskappe Group 40km M Bronlund Fjord Group .. Buen Formation lee margin L Portfjeld Formation Fig. 2. Outcrops ol' thl;' Buen FormaliolI in central North Grccnbnd showing thc localily for lho:: l.owcr CImbrian lagcrstiittcn al Sirius P,lsscL During July - e(}r!y August IYYI, <I second 4-mall brian record af this group (Ramsk6ld & llol! Xian­ cxpedition vtsited Sirius Pa<:-isct. As in t989, financial guang. 199t; Rellgtsoll. lY9l). suppon for thc ficldwork was provided by a grant from Despite limitations imposcd hl' struc!uraJ cornplexity the Carlsherg Founclation. Copcnhagcn. Transport hoth and intermittant exposure, fieldwark in 1991 rcsu1tcd in to and \vithin North Greenland was co-ordinatcd with an increased understancling af the local stratigraphy and scvcral Dlher grollps from Dnnish SCiCfltific institutions the sedimclltolagical evolution af the iml1lediate al"ca of under a logisIie umbrelln providcd by Dansk Polarcen~ the fossil locality. Thc stccply-dipping fossiliferous t<.:r. Three weeks of cOllecting bcnefittcu from excellent mudstoncs uf the Buen Fonnation occur in dase prox­ wcalher. in contrasl Io the pOOl" conciitiOlls \vhich prc­ imity to horizontally-bcdclcJ platform carhonates of tlle vailed ciuring tlle IYS9 visit. stratigraphically older Portfjeld Fonnation; this contact Collecting during 1991 yiclded marc than 3000 fossi­ has hcen inlerpreted pn.:viously as a slruclural feature, liferous slabs and confirmed the image af the fauna citllcr a down-Io-basill (i.e. llorth) normal fault Ol' a cstahlishcd alrc(ldy in 1989. A number of addiliona\ back-thrllst (A. K. Higgins. personal cOlTlnluni<.:atioll. spccimcllS ol' halkicriids wcre obtained, toget her \Vith 191)1). Dc.tailed mapping and tlie oc<.:urrence. Jocal1)'. of numcrous anhropods witll prescrvecl sort parts. Two carbonate slope LICies at the conlacL however. suggesl spccimcIlS uf a possihlc onychophoran are af particular that lhe houndary defines the original northcrn margin illtcrcst an aceount af currcnt discussions af the Calll- of thc Portfjeld Forrmltion carbonatc platform. This 50 eonc1usion is compatibie with the regional palaeogeo­ Conway Morris, S. 1979: The Burgess ShaJe (Middle Cam­ graphy (Higgins et al., 1991) and implies that the fossil­ brian) fauna. Ann. Rev. Ecol. System. 10,327-349. bearing mudstones of the Buen Formation were depos­ Conway Morris, S. 1986: The community structure of the Mid­ ited basinward of the shelf edge, in a transitional 'slope' dIe Cambrian Phyllopod bed (Burgess Shale). Palaeontology setting. 29,423-467. Thrust repetition was demonstrated within strata of Conway Morris, S. & Peel, J. S. 1990: Articulated halkieriids from the Lower Cambrian of north Greenland. Nature 345, the Buen Formation north of the eontaet with the Portf­ 802-805. jeld Formation. Thus, minor teetonie modification of Conway Morris, S., Peel, J. S., Higgins, A. K., Soper, N. J. the boundary between the Buen Formation and the & Davis, N. C.1987: A Burgess shale-like fauna from the Portfjeld Formation ean not be prec1uded. Preliminary Lower Cambrian of North Greenland. Nature 326, 181-183. eorrelation between the fossil-bearing, mud-dominated Gould, S. J. 1989: Wonderfullife. The Burgess shale and the strata of the Buen Formation north of the shelf edge and nature ofhistory, 347 pp. New York: W. W. Norton & Co. the Buen Formation exposed in outliers on top of the Higgins, A. K., Ineson, J. R., Peel, J. S., Surlyk, F. & Sønder­ Portfjeld Formation, in the area south of the edge, ho1m, M. 1991: Lower PaJaeozoic Franklinian Basin of suggests that the former were deposited folIowing the North Greenland. Bul!. Grønlands geol. Unders. 160, 71­ 139. initial transgression of the karstified Portfjeld platform; Hou Xian-guang & Bergstrom, J. 1991: The arthropods of the this is compatibie with the stratigraphie position of the Lower Cambrian Chengjiang fauna, with relationships and Sirius Passet fauna suggested previously, namely within evolutionary significance. In Simonetta, A. M. & Conway the lower part of the Buen Formation (Peel, 1990). Morris, S. (ed.) The early evolution of Metazoa and the significance ofproblematic taxa, 179-187. Cambridge: Cam­ Acknowledgements. We thank fellow expedition member bridge Univ. Press. Mona Bjørklund for assistance in the field and S. Hauge An­ Muller, K. J. 1985: Exceptional preservation in calcareous dersson (Dansk Polarcenter) for his organisational expertise. nodules. Phil. Trans. Roy. Soc. Lond. B311, 67-73. The programme received financial support from the Carlsberg Peel, J. S. 1990: Studying the early history of life in Greenland. Foundation, and logistic support from the Royal Danish Air Rapp. Grønlands geol. Unders. 148,54-56. Force and the Geological Survey of Greenland. Peel, J. S. 1991: The Classes Tergomya and HelcioneIIoida, and early molluscan evolution. Bul!. Grønlands geol. Un­ ders. 161, 11-65. References Ramskold, L. & Hou Xianguang 1991: Newearly Cambrian animal and onychophoran affinities of enigmatic metazoans. Barthel, K. w., Swinburne, N. H. M. & Conway Morris, S. Nature 351, 225-228. 1990: Solnhofen: a study in Mesozoic palaeontology, 236 pp. SeiIacher, A., Reif, W.-E. & Westphal, F. 1985: Sedimentolog­ Cambridge: Cambridge U. P. icai, ecological and temporal patterns of fossil lagerstatten. Bengtson, S. 1991: OddbaIIs from the Cambrian start to get Phil. Trans. Roy. Soc. Lond. B311, 5-23. even. Nature 351, 184-185. Sturmer, W., Schaarschmidt, F. & Mittmeyer, H.-G. 1980: Briggs, D. E. G. & Crowther, P. R. 1990: Palaeobiology. A Versteinertes Leben im Rontgenlicht, 80 pp. Frankfurt: Ver­ synthesis, 583 pp. Oxford: BlackweII Sci. PubI. lag W. Kramer. Chen Jun-yuan & Erdtmann, 0.-0. 1991: Lower Cambrian Whittington, H. B. 1985: The Burgess Shale, 151 pp. New lagerstiitte from Chengjiang, Yunnan, China: insights for Haven: Yale U.P. reconstructing early metazoan life. In Simonetta, A. M. & Conway Morris, S. (ed.) The early evolution ofMetazoa and the significance of problematic taxa, 57-76. Cambridge: J. S. P., Geological Survey of Greenland, Copenhagen. Cambridge Univ. Press. S. C. M., Dept of Earth Sciences, University of Cambridge, Chen Jun-yuan, Bergstrom, J., Lindstrom, M. & Hou Xian­ Downing Street, Cambridge CB23EQ, u.K. guang 1991: Fossilized soft-bodied fauna. Natl Geographic J. R. I., Geological Survey of Denmark, Thoravej 8, DK-2400 Res. & Explor. 7(1), 8-19. Copenhagen NV, Denmark..